Sony Ericsson W810

The phone comes with an adapter to use standard headphones on the phone. I've used different headphones other than the ones that come with the phone with no problem. Today I brought in a pair of portable Sony speakers (the cheap $10 ones from Walmart, so nothing fancy) and they won't work with the phone. It still plugs into the standard headphone jack on the adapter so there should be no problem. Still, as soon as I plug the speakers in the music stops playing through the phone speakers and just doesn't play through the normal speakers.

Does anyone know why that would happen? Do I have to buy the special speaker set specifically for the phone? Is there perhaps a different brand or model of portable speakers anyone else has tried wit...
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